In developing nations, noise pollution has been studied less intensively — but it’s probably even worse there. Even a brief visit to cities such as Jakarta, Beijing, Nairobi, or Mexico City reveals that blaring traffic noise is a serious and growing menace.

And it’s only going to worsen in coming years. In 2010, we had about 1 billion motorized vehicles on Earth. By 2030, we’ll have 2 billion—twice as many noisy, vibrating, smoke-belching machines all around us.

Many large animals — from grouse to wolves to elk — tend to avoid roads, most likely because of road noise.

For animals large and small, noisy roads and people are invisibly degrading their habitat.

The only answer — for the sanity and health of humanity and nature alike — it to save substantial areas as ‘sonic-free zones’, where the burble of a brook or a calling bird is fine, but the blaze of a chainsaw or roar of a four-wheel-drive vehicle is not.